Mutation in GNE Downregulates Peroxiredoxin IV Altering ER Redox Homeostasis
- 277 Downloads
GNE myopathy is a rare neuromuscular genetic disorder characterized by early adult onset and muscle weakness due to mutation in sialic acid biosynthetic enzyme, UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase (GNE). More than 180 different GNE mutations are known all over the world with unclear pathomechanism. Although hyposialylation of glycoproteins is speculated to be the major cause, but cellular mechanism leading to loss of muscle mass has not yet been deciphered. Besides sialic acid biosynthesis, GNE affects other cellular functions such as cell adhesion and apoptosis. In order to understand the effect of mutant GNE protein on cellular functions, differential proteome profile of HEK293 cells overexpressing pathologically relevant recombinant mutant GNE protein (D207V and V603L) was analyzed. These cells, along with vector control and wild-type GNE-overexpressing cells, were subjected to two-dimensional gel electrophoresis coupled with mass spectrometry (MALDI-TOF/TOF MS/MS). In the study, 10 differentially expressed proteins were identified. Progenesis same spots software revealed downregulation of peroxiredoxin IV (PrdxIV), an ER-resident H2O2 sensor that regulates neurogenesis. Significant reduction in mRNA and protein levels of PrdxIV was observed in GNE mutant cell lines compared with vector control. However, neither total reactive oxygen species was altered nor H2O2 accumulation was observed in GNE mutant cell lines. Interestingly, ER redox state was significantly affected due to reduced normal GNE enzyme activity. Our study indicates that downregulation of PrdxIV affects ER redox state that may contribute to misfolding and aggregation of proteins in GNE myopathy.
KeywordsGNE myopathy UDP-N-acetylglucosamine-2-epimerase/N-acetylmannosamine kinase Peroxiredoxin IV Sialic acid ROS MERO-GFP ER Stress
Reactive Oxygen Species
Protein Disulfide Isomerase
Two-dimensional gel electrophoresis
Endoplasmin reticulum oxidoreductase
Mammalian endoplasmic reticulum-localized RedOx-sensitive Green Fluorescent Protein
We acknowledge Prof Fumihiko Urano, Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO, USA, for MERO-GFP construct. We also thank Prof. Alok Bhattacharya (School of Life Sciences, Jawaharlal Nehru University, New Delhi) and Prof. Sudha Bhattacharya (School of Environmental Sciences, Jawaharlal Nehru University, New Delhi) for thoughtful discussions and progressive comments during the project. We thank Mr. Ashok Kumar Sahu, Technical Officer, Advanced Instrumentation Research Facility, JNU for confocal facility.
This work was supported by the Department of Science and Technology-PURSE-II (DST/SR/PURSE Phase II/11) and University Grants Commission-UPOE II (Project ID: 16), Govt. of India.
Compliance with Ethical Standards
Conflict of interest
Authors declare no conflict interest.
- Hinderlich, S., Salama, I., et al. (2004). The homozygous M712T mutation of UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase results in reduced enzyme activities but not in altered overall cellular sialylation in hereditary inclusion body myopathy. FEBS Letters, 566(1–3), 105–109.CrossRefPubMedGoogle Scholar
- Wang, Z., Sun, Z., et al. (2006). Roles for UDP-GlcNAc 2-epimerase/ManNAc 6-kinase outside of sialic acid biosynthesis: Modulation of sialyltransferase and BiP expression, GM3 and GD3 biosynthesis, proliferation, and apoptosis, and ERK1/2 phosphorylation. Journal of Biological Chemistry, 281(37), 27016–27028.CrossRefPubMedGoogle Scholar
- Weidemann, W., Stelzl, U., et al. (2006). The collapsin response mediator protein 1 (CRMP-1) and the promyelocytic leukemia zinc finger protein (PLZF) bind to UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase (GNE), the key enzyme of sialic acid biosynthesis. FEBS Letters, 580(28–29), 6649–6654.CrossRefPubMedGoogle Scholar